CN115282407A

CN115282407A - Syringe plunger with dynamic seal

Info

Publication number: CN115282407A
Application number: CN202210757073.XA
Authority: CN
Inventors: M.斯万特纳; M.麦克德莫特
Original assignee: Bayer Healthcare LLC
Current assignee: Bayer Healthcare LLC
Priority date: 2017-01-06
Filing date: 2018-01-04
Publication date: 2022-11-04
Also published as: DK3565619T3; CN110167616A; US20220288322A1; EP4292627A3; CN110167616B; US11969582B2; EP4292627A2; US20200086057A1; HUE063479T2; AU2018205704B2; ES2960350T3; AU2018205704A1; JP2020513928A; FI3565619T3; PL3565619T3; WO2018129116A1; JP7114598B2; CA3049207A1; PT3565619T; EP3565619B1

Abstract

The invention discloses a plunger, a syringe and a method for manufacturing the plunger and the syringe. The plunger includes a support ring and a cap disposed over and coupled to the support ring. A cavity defining a predetermined volume is defined between the support ring and the cover. The syringe includes a barrel defining an inner wall and the plunger is inserted into the barrel.

Description

Syringe plunger with dynamic seal

The present application is a divisional application of chinese national phase application 201880006030.X entitled "syringe plunger with dynamic seal" of PCT international application PCT/US2018/012284, filed 1, month 4, 2018.

Cross Reference to Related Applications

This application claims priority from U.S. provisional patent application No.62/443,302, filed on day 06 of 2017, the entire disclosure of which is incorporated herein by reference.

Technical Field

The present invention relates generally to medical fluid delivery applications, and in particular to fluid injection systems including a fluid injector, a syringe, and a plunger within the syringe. More particularly, the present invention relates to syringe plungers having dynamic seals.

Background

In many medical diagnostic and therapeutic procedures, medical practitioners (such as physicians) inject patients with fluids. In recent years, several injector-actuated syringes and powered injectors for pressurized injection of fluids (contrast media) have been developed for use in imaging procedures, such as angiography, computed Tomography (CT), ultrasound, and magnetic resonance imaging. Generally, these power injectors are designed to deliver a preset amount of contrast media and/or saline at a preset flow rate using one or more disposable or refillable syringes.

Automatic injection mechanisms typically include a syringe connected to a powered injector using a linear actuator. The linear actuator operates a movable piston configured to engage a plunger inserted into the barrel of the syringe. The interface or engagement between the piston and plunger includes reversible mechanical locking structures, such as threads, undercuts, pins, swivels, snap-fit connections, and the like, for establishing and maintaining a connection between the piston and plunger.

The plunger/piston interface should be strong enough to retract the plunger through the barrel in a proximal direction to draw fluid into the syringe and to advance the plunger through the barrel in a distal direction to expel fluid contained therein.

In addition to being strong enough to maintain a good connection between the piston and plunger during use, the interface should also be removable so that the syringe and plunger can be discarded after use. With a mechanical locking structure, to disengage the piston from the plunger, the user orients the piston and plunger for disengagement, such as by rotating the syringe, to properly align locking features on the piston and plunger, or pulls the piston away from the plunger with sufficient force to overcome the locking structure. Once the piston is disengaged from the plunger, the used syringe and plunger may be discarded.

The challenge with syringe plunger sealing is insufficient sealing during the injection process. It is desirable to provide a dynamic seal-enhancing seal for a syringe plunger during an injection procedure in which compression is generated when the syringe is under injection pressure. Preload compression is undesirable because during the shelf life of the syringe, the plastic components undergo deformation or creep (creep) that compromises the formation of a sufficient seal under injection pressure conditions. Furthermore, it is desirable to limit compression due to automated assembly processes where low pressure during manufacturing is desired. Accordingly, various aspects of the syringe plunger with dynamic sealing described herein overcome these drawbacks.

Disclosure of Invention

While auto-injectors are well known, there is a continuing need for improved fluid delivery systems that make the injection process simpler for medical personnel. With respect to the present invention, a syringe having a plunger with a dynamic seal is presented. It is also desirable to have such a plunger that has a dynamic seal that slides easily through the inner wall of the barrel of the syringe, but is configured to provide a good effective seal against the inner wall of the barrel during the injection process to prevent leakage of the substance contained therein.

In view of the above, there is a need for syringes having plungers with dynamic seals that may be used with injectors (such as power injectors). According to one aspect of the invention, the plunger with dynamic seal compresses under injection pressure. Initially, under relatively low pressure conditions, the compression between the plunger and the inner wall of the barrel is low. The compression increases under injection pressure conditions of the fluid delivery system, and thus increases the seal between the plunger and the inner wall of the barrel of the syringe.

In one aspect, a syringe plunger with a dynamic seal is provided. The syringe plunger with dynamic seal includes a support ring and a cover disposed over and coupled to the support ring, wherein an air chamber defining a predetermined volume is defined between the support ring and the cover.

In another aspect, a syringe is provided that includes a plunger having a dynamic seal. The syringe includes a barrel defining an inner wall and a plunger positioned within the interior of the barrel. The plunger includes a support ring and a cover disposed over and coupled to the support ring, wherein an air chamber defining a predetermined volume is defined between the support ring and the cover.

In addition to the foregoing, various other method and/or system and/or program product aspects are set forth and described in the teachings of the present invention, such as in the text (e.g., claims and/or embodiments) and/or drawings.

Various aspects of the invention are also described in the following clauses.

Clause 1: a plunger, comprising: a support ring; and a cover disposed over and coupled to the support ring, wherein the support ring and the cover define an air chamber therebetween, the air chamber defining a predetermined volume.

Clause 2: the plunger of clause 1, further comprising a conical cap disposed over the cover.

Clause 3: the plunger of claim 2, wherein the conical cap includes an overmolded element disposed thereon.

Clause 4: the plunger of any of claims 1-3, wherein the cap further comprises a first annular rib and a second annular rib.

Clause 5: the plunger of any of claims 1-4, wherein the cap comprises: a conical cap; a cylindrical sidewall having at least one annular rib; and a flange to engage the support ring.

Clause 6: the plunger of any of clauses 1-5, wherein the support ring comprises a conical cap defining an included angle greater than about 90 °.

Clause 7: the plunger of clause 6, wherein the conical cap of the support ring defines an included angle that is greater than about 90 ° and less than about 120 °.

Clause 8: the plunger of clauses 6 or 7, wherein the conical cap of the support ring and the conical cap of the cap define an angle therebetween.

Clause 9: the plunger of clause 8, wherein the angle defined between the conical cap of the support ring and the conical cap of the cover is greater than 0 ° and less than about 30 °.

The clause 10: the plunger of any of claims 1-9, wherein the support ring comprises: a shoulder; and defines an annular groove between the shoulder and the conical cap to receive a flange defined by the cap.

Clause 11: the plunger of any one of clauses 1-10, wherein the predetermined volume is selected within a range between 0.1mL and 10mL.

Clause 12: a syringe, comprising: a barrel defining an inner wall; and a plunger positioned within the inner wall of the barrel, the plunger comprising: a support ring; and a cover disposed above and coupled to the support ring, wherein an air chamber defining a predetermined volume is defined between the support ring and the cover.

Clause 13: the syringe of claim 12, wherein the plunger comprises a conical cap disposed over the cap.

Clause 14: the needle cartridge of claim item 13, wherein the conical cap comprises an overmold element disposed thereon.

Clause 15: the syringe of any of claims 12-14, wherein the cap further comprises a first annular rib and a second annular rib that form a seal with the inner wall of the barrel.

Clause 16: the syringe of any one of claims 12 to 15, wherein the cap comprises: a conical cap; a cylindrical sidewall having at least one annular rib; and a flange to engage the support ring.

Entry 17: the syringe of any of clauses 12 to 16, wherein the support ring comprises a conical cap defining an included angle greater than about 90 °.

Clause 18: the syringe of clause 17, wherein the conical cap of the support ring defines an included angle that is greater than about 90 ° and less than about 120 °.

Clause 19: the syringe of

clause

17 or 18, wherein the conical cap of the support ring and the conical cap of the cover define an angle therebetween.

The clause 20: the needle cartridge of item 19, wherein the angle defined between the conical cap of the support ring and the conical cap of the cover is greater than 0 ° and less than about 30 °.

Clause 21: the needle cartridge of any one of claims 12-20, wherein the support ring comprises: a shoulder; and an annular groove defined between the shoulder and the conical cap to receive a flange defined by the cap.

Clause 22: the syringe of any one of clauses 12 to 21, wherein the predetermined volume is selected within a range between 0.1mL and 10mL.

The clause 23: a method of manufacturing a plunger, the method comprising: providing a support ring comprising a first conical cap, a shoulder and defining an annular groove between the shoulder and the conical cap; attaching a cover to the support ring, the cover comprising a second conical cap, a cylindrical sidewall, and a flange to engage the annular groove of the support ring; and attaching a third conical cap to the second conical cap of the lid.

Item 24: a method of manufacturing a syringe, comprising: providing a syringe barrel; a plunger is manufactured according to a method comprising: providing a support ring comprising a first conical cap, a shoulder and defining an annular groove between the shoulder and the conical cap; attaching a cover to the support ring, the cover comprising a second conical cap, a cylindrical sidewall, and a flange to engage the annular groove of the support ring; and attaching a third conical cap to the second conical cap of the lid; and inserting the plunger into the syringe barrel.

The foregoing is a summary and thus contains, by way of illustration, simplifications, generalizations, inclusions, and/or omissions of detail; consequently, those skilled in the art will appreciate that the summary is illustrative only and is not intended to be in any way limiting. Other aspects, features, and advantages of the devices and/or processes and/or other subject matter described herein will become apparent in the teachings set forth herein.

Further, it is to be understood that any one or more of the forms, expressions of form, examples described below can be combined with any one or more of the forms, expressions of form, and examples described below.

The above summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, and features described above, further aspects, and features will be appreciated by reference to the drawings and the following detailed description.

Drawings

The novel features of the described form are set forth with particularity in the appended claims. The described form, however, both as to organization and method of operation, may best be understood by reference to the following description, taken in conjunction with the accompanying drawings in which:

FIG. 1 is a side view of a syringe according to one aspect of the present invention;

FIG. 2 is a schematic cross-sectional view of a syringe interface having a piston and plunger according to one aspect of the present invention;

FIG. 3 is a cross-sectional view of a syringe plunger system according to an aspect of the present invention;

FIG. 4 is a cross-sectional view of one aspect of a syringe plunger system having a dynamic seal according to one aspect of the present invention;

FIG. 5A is a cross-sectional view of an aspect of the syringe plunger system having a dynamic seal shown in FIG. 4 in an initial compressed state, according to an aspect of the present invention;

FIG. 5B is a cross-sectional view of an aspect of the syringe plunger system having a dynamic seal shown in FIG. 5A in a compressed state, according to an aspect of the present invention;

fig. 6-11 illustrate several views of a support ring structure including an included angle, wherein:

FIG. 6 is a perspective view of a support ring according to one aspect of the present invention;

FIG. 7 is a perspective view of a support ring according to one aspect of the present invention;

FIG. 8 is a plan view of a support ring according to one aspect of the present invention;

FIG. 9 is an elevation view of a support ring according to one aspect of the present invention;

FIG. 10 is a bottom view of a support ring according to one aspect of the present invention;

FIG. 11 is a cross-sectional view of the support ring (as shown in FIG. 10) taken along section line 11-11 in accordance with an aspect of the present invention;

fig. 12 is a cross-sectional view of a syringe plunger system with dynamic sealing in a transport configuration, according to an aspect of the present invention;

fig. 13 is a cross-sectional view of the syringe plunger system with dynamic sealing illustrated in fig. 12 in an initial compressed state in accordance with an aspect of the present invention;

FIG. 14 is a cross-sectional view of the syringe plunger system with dynamic seals shown in FIG. 12 at an operating injection pressure according to an aspect of the present invention;

fig. 15 is a cross-sectional view of the syringe plunger system 200 with dynamic seal shown in fig. 12 in a compressed state approaching or exceeding a maximum injection pressure, in accordance with an aspect of the present invention;

fig. 16 is a graphical representation of the maximum pressure that the syringe plunger system described in connection with fig. 4-15 withstands after a continuous pressurization cycle, in accordance with an aspect of the present invention;

fig. 17 is an illustration of a condition of maximum pressure tolerated by the syringe plunger system described in connection with fig. 4-15 after a sustained pressurization cycle, in accordance with an aspect of the present invention;

FIG. 18 is a graphical representation of the relationship of seal pressure as a function of plunger included angle in accordance with an aspect of the present invention; and

fig. 19 is an illustration of optimal gap sizes for the air chamber described for dynamic sealing of the syringe plunger system, according to an aspect of the present invention.

Detailed Description

Before explaining in detail the various forms of syringe plunger with dynamic sealing, it should be noted that the illustrative forms are not limited in their application or use to the details of construction and arrangement of parts illustrated in the accompanying drawings and description. The illustrative forms may be implemented or incorporated in other forms, variations and modifications, and may be practiced or carried out in various ways. Furthermore, unless otherwise indicated, the terms and expressions employed herein have been chosen for the purpose of describing the illustrative form for the convenience of the reader and are not for the purpose of limiting the same.

Further, it should be understood that any one or more of the forms, expressions of form, examples described below can be combined with any one or more of the forms, expressions of form, and examples described below.

Various forms pertain to syringe plungers having dynamic seals to provide enhanced sealing during an injection procedure under injection pressure conditions. Referring to fig. 1, in one aspect, the syringe 10 includes a barrel 12, a plunger 14, and a plunger rod 17. The plunger 14 is slidably inserted in the barrel 12. The plunger 14 may be removably or non-removably or integrally connected to the plunger rod 17. The proximal end 15 of the plunger rod 17 extends outwardly from the proximal end 13 of the barrel 12 and is configured to interface with an external piston (not shown) configured to be driven by a fluid injector, such as a power or auto injector. The interface between the plunger rod 17 and the external piston of the barrel 10 may include a connecting surface structure (such as a mating element 20) extending from the proximal end 15 of the plunger rod 17. The mating element 20 is configured to engage with an external piston. The outer piston may comprise a piston rod (not shown). In an alternative aspect, the plunger 14 may interface directly with the external piston.

In use, the external plunger is brought into contact with mating element 20 of barrel 10 and engages mating element 20. In one aspect, the syringe may be disposable. Various techniques may be employed to engage the outer piston with mating element 20. Once engagement is established, the outer piston may be retracted to fill the syringe 10 with fluid or actuated in a proximal direction to expel fluid contained therein. Once the fluid is expelled, a sliding body (not shown) moves in a proximal direction to disengage the outer piston from the mating element 20. Once disengaged, the user may discard the cartridge 10. Commonly assigned U.S. publication No.2016/0151570, U.S. Pat. No.9,173,995, entitled VACUUM SYSTEM FOR SYRINGE INTERFACE, filed 7/9.2014; 9,199,033; and 9,700,670, and additional examples of syringes are found in U.S. patent application No.15/541,573, the disclosures of which are incorporated herein by reference.

Referring to fig. 2, the syringe 10 includes a barrel 12, which may be cylindrical, and a plunger 14, as well as the method of pushing and retracting the plunger 14 through the barrel 12 described in connection with fig. 1. The syringe 10 generally includes a barrel 12, a plunger 14, and a piston 18 for advancing and retracting the plunger 14 through the barrel 12. The piston 18 may include a piston head 16 for engaging the plunger 14. Piston 18 may optionally include a handle (not shown) that allows a user to manually advance plunger 14. Alternatively, the piston 18 may be connected to a mechanical mechanism (such as a powered injector, powered linear actuator, or fluid injector) for automatically driving the piston head 16 and plunger 14 through the barrel 12. The piston 18 may be made of a rigid plastic. Examples of piston-to-plunger engagement mechanisms can be found, for example, in U.S. patent nos. 9,480,797 and 7,666,169, the disclosures of which are incorporated herein by reference.

The barrel 12 is adapted to contain a fluid F (such as a medicament, biological solution, saline, or contrast media) to be injected into a patient. The barrel 12 extends longitudinally from a proximal end 21 (proximal to the syringe device) to a distal end 22 and is configured to expel fluid F from the distal end 22 of the barrel 12. The distal end 22 may contain an outflow port 24 such as a nozzle (nozzle), needle cannula or catheter tubing. The barrel 12 may be formed of any suitable biocompatible and medical grade material including glass, metal, ceramic, plastic, rubber, or combinations thereof.

The plunger 14 is adapted to be slidably inserted into the barrel 12 and includes a cylindrical body 26 formed of an elastomeric material, a sidewall 28, and a conical cap 30. The plunger 14 has an outer diameter ED that corresponds to the inner diameter ID of the barrel 12 such that a fluid seal is formed between the sidewall 28 and the inner wall 29 of the barrel 12. In a particular aspect, the sidewall 28 includes one or more annular ribs 32 extending radially from the sidewall 28. The annular rib 32 is adapted to contact and compress against the inner wall 29 to form a fluid tight seal, and is adapted to slide against the inner wall 29 of the barrel 12 as the plunger 14 is advanced or retracted, while maintaining a fluid tight seal. The annular rib 32 reduces the contact surface area against the inner wall 29 of the barrel 12, which reduces friction between the barrel 12 and the plunger 14 and allows the plunger 14 to slide more easily through the barrel 12.

The plunger 14 may further include an annular shoulder 42 or ring positioned on the proximal end of the plunger 14. Annular shoulder 42 contacts a corresponding portion of piston 18 or piston head 16 to exert additional urging force against plunger 14.

The sidewall 28 is flexible and can deform outwardly to increase the size of the opening and cavity defined by the interior portion of the plunger 14 to receive the piston head 16 and/or the support ring 116. In a particular aspect, portions of the sidewall 28 may be substantially hollow and contain an annular channel (not shown) to reduce the structural integrity of the sidewall 28, thereby further increasing flexibility.

In use, the piston head 16 is inserted into the cavity defined by the plunger 14, thereby establishing a removable engagement therebetween. Engagement is sufficient to maintain connection between plunger 14 and piston head 16 as plunger 14 is advanced through barrel 12 and as plunger 14 is retracted from barrel 12. Thus, the engagement must be strong enough to counteract both the initial frictional disengagement force created by contact between the sidewall 28 and/or the annular rib 32 of the plunger 14 and the inside surface of the barrel 12, as well as the dynamic frictional forces created when the plunger 14 slides through the barrel 12 and the at least partial vacuum created when the plunger 14 is retracted to draw the liquid F into the syringe.

Fig. 3 is a cross-sectional view of a syringe plunger system 100 according to one aspect. The syringe plunger system 100 includes an included angle of about 90 deg. (e.g., from 85 deg. to 95 deg.). As used herein, the term "about" when referring to the angle of the plunger system means plus or minus 5 °. The syringe plunger system 100 includes a plunger 102 disposed within a barrel 104 of a syringe. The barrel 104 defines an inner wall 106 configured to slidably receive the plunger 102. The plunger 102 includes a support ring 116, a cap 114 disposed on and snapped over the support ring 116, and a conical cap 110 disposed over the cap 114. When the plunger 102 is under injection pressure conditions, the plunger 102 is deflected axially and the cap 114 is deflected radially toward the inner wall 106 of the barrel 104 to provide a greater seal under injection pressure conditions. In a particular aspect, the conical cap 110 can include an overmold element 112.

The cover 114 includes a cylindrical sidewall 108, a conical cap 160, and a flange 162 (such as a protruding rim (rim) or edge (edge)) for coupling the cover 114 to the support ring 116. The lid 114 includes one or more annular ribs, such as a first annular rib 120 and a second annular rib 122. The first annular rib 120 is received in a first annular groove 124 defined by the inner wall 106 of the barrel 104, and the second annular rib 122 is received in an annular groove 126 also defined by the inner wall 106 of the barrel 104.

The support ring 116 includes an annular shoulder 154, a conical cap 152, and an annular groove 118 defined therebetween to receive a flange 162 of the cover 114. The conical cap 152 of the support ring 116 defines aboutAngle theta of 90 deg ₁ And an annular groove 118 to receive the cap 114 portion of the conical cap 110. The support ring 116 defines an interior volume 132 within the conical cap 160. At least one orifice (alert) 134 is defined by the backing ring 116 to provide an exit path for air between the cap 114 and the backing ring 116 during pressurization of the injection. The air is discharged back out of the barrel 104 of the syringe through the at least one aperture 134 and out of the fluid path.

An air chamber 128 is defined between a tip 150 of a conical cap 152 of the support ring 116 and a conical cap 160 of the cover 114. The conical cap 160 of the cover 114 contacts the conical cap 152 of the support ring 116 at the interface 130 and is supported by the conical cap 152. There is no gap or air cavity at the interface 130.

Fig. 4 is a cross-sectional view of a syringe plunger system 200 having a dynamic seal according to another aspect. A syringe plunger system 200 is shown prior to injection pressurization. Syringe plunger system 200 includes an included angle θ of greater than about 90 ₂ . The included angle θ increases beyond about 90 ° as will be described below ₂ Increasing the sealing pressure limit of the syringe plunger system 200. Alternatively, syringe plunger system 200 includes an included angle θ of about 90 ° on conical cap 252 of support ring 216 ₂ And an included angle on the conical cap 260 of the cover 214 of less than about 90. The syringe plunger system 200 includes a plunger 202 disposed within a syringe barrel 204 of a syringe. The syringe barrel 204 defines an inner wall 206 configured to slidably receive the plunger 202. Plunger 202 includes a support ring 216, a cap 214 disposed over support ring 216 and coupled to support ring 216, and a conical cap 210 disposed over cap 214. In one aspect, the cover 214 may be snap fit to the support ring 216. When the plunger 202 is under injection pressure conditions, the plunger 202 is deflected axially and the cap 214 is deflected radially toward the inner wall 206 of the syringe barrel 204 to provide a greater seal under injection pressure conditions. The conical cap 210 may include an overmold element 212.

The cover 214 includes a cylindrical sidewall 208, a conical cap 260, and a flange 262 (such as a protruding rim or edge) for coupling the cover 214 to the support ring 216. The lid 214 includes a first annular rib 220 and a second annular rib 222. The first annular rib 220 is received in a first annular groove 224 defined by the inner wall 206 of the syringe barrel 204, and the second annular rib 222 is received in a second annular groove 226 also defined by the inner wall 206 of the syringe barrel 204.

The support ring 216 includes an annular shoulder 254, a conical cap 252, and an annular groove 218 defined therebetween to receive the flange 262 of the cap 214. The conical cap 252 of the support ring 216 defines an included angle θ greater than about 90 ₂ And an annular groove 218 to receive the cap 214 portion of the conical cap 210. In the illustrated example, the included angle θ ₂ Is 96 deg., although the invention is not limited in this context as the angle theta may be calculated ₂ To produce the optimum effect of dynamic sealing. The support ring 216 defines an interior volume 232 within the conical cap 252. At least one orifice 234 is defined by the support ring 216 to provide an exit path for air between the cap 214 and the support ring 216 during injection pressurization. The air is discharged back out of the syringe barrel 204 of the syringe through the at least one orifice 234 and out of the fluid path.

The conical cap 252 of the support ring 216 and the conical cap 260 of the cover define a gap or air chamber 230 therebetween. An air chamber 230 or "gap" is defined along the conical portion of the plunger 202 between the support ring 216 and the cover 214. Angle theta ₃ Is defined between the support ring 216 and the cover 214, and defines an air chamber 230. Angle theta ₃ May vary, for example, from a value greater than 0 ° to a value less than about 30 °, and nominally about 6 °. The air chamber 230 defines a predetermined compliance volume such that when the syringe plunger system 200 is subjected to injection pressurization, the overmold element 212 and the cover 214 deform and flex into the compliance volume defined by the air chamber 230. The injection pressure applies an axial force to the over-mold element 212 and the cap 214, deforming them and compressing the air cavity 230, which applies a radial force to the first and second

annular ribs

220, 222 to engage the respective first and second

annular grooves

224, 226 and/or against the sidewall 206 to create a dynamic seal under injection pressure conditions. The volume of the air chamber 230 at the included angle θ ₂ And increases when increasing. Can pass through an included angle theta ₂ The volume of the air chamber 230 is optimized. Therefore, it can be based on the included angle θ ₂ Increasing or decreasing the compliance volume. Included angle theta ₂ May vary, for example, from a value greater than about 90 to a value less than about 120, and nominally about 96. The compliance volume may vary, for example, from about 0.1mL to 10mL. As shown in fig. 4, at an included angle θ of about 96 ° ₂ In the case of (2), the compliance volume is about 1mL. The size of the air cavity 230 and "gap" translates into the sealing pressure of the dynamic seal. The optimal size of the air chamber 230 may be calculated to produce an optimal dynamic seal for a particular syringe/syringe application. This optimal effect may be, for example, equivalent to a maximum added compression for the seal.

While the term "air chamber" is used herein to describe the compressible volume between the conical cap 252 of the support ring 216 and the conical cap 260 of the cover, other compressible materials may also be included in the volume between the conical cap 252 of the support ring 216 and the conical cap 260 of the cover. For example, in certain aspects, a volume between the conical cap 252 and the conical cap 260 may be filled with a bladder containing a compressible fluid (e.g., a compressible gas or other fluid). In another aspect, a compressible material (such as an elastomeric material having a low modulus that can deform under pressure loads associated with an injection process) may be used to fill the volume between the conical cap 252 and the conical cap 260. Non-limiting examples may include compressible or deformable materials (such as thermoplastic elastomers or foamed materials) that compress to allow dynamic sealing under pressure loads typical of injection processes. In particular aspects, predictable compression, and thus predictable control over the dynamic seal between the plunger sidewall and the inner wall of the syringe, may be achieved by selecting materials having a particular compliance or compression factor at a desired pressure load. In certain aspects, the compression of the material will be reversed without the pressure load of the injection process.

In one aspect, the body of the syringe barrel 204 may be made of polyethylene terephthalate (commonly abbreviated PET), such as, for example, eastman MN052 PET. The support ring 216 may be made of a Polycarbonate (PC) thermoplastic polymer or any suitable medical grade polymer that is strong, and may optionally be transparent and that can be easily processed, molded, and thermoformed, such as, for example, lexan 141. The cover 214 may be made of a thermoplastic elastomer (TPE) (sometimes referred to as thermoplastic rubber) or other blend of polymers having both thermoplastic and elastomeric properties, such as plastic and rubber, such as Santoprene 181-5, for example. The cover 214 may optionally be transparent or translucent. Thermoplastics are desirable because of their ability to be relatively easily used in manufacturing and injection molded. The overmold element 212 may be made of polypropylene (PP) (also referred to as a polypropylene thermoplastic polymer), such as, for example, polypropylene P5M4K-046, and may optionally be transparent or translucent. The syringe barrel 204, support ring 216, cover 214, and overmold element 212 are made from medical grade plastics and materials.

Fig. 5A is a cross-sectional view of one aspect of the syringe plunger system 200 with dynamic sealing shown in fig. 4 in an initial compressed state. In the example illustrated in FIG. 5A, the included angle θ ₂ Is approximately 96 deg.. However, as described in connection with FIG. 4, the included angle θ may be varied ₂ To optimize dynamic sealing. The compliant volume defined by the air chamber 230 is an initial compressed state after an initial application of injection pressure 240 (represented by the vertical arrow) and causes axial deflection of the plunger 202 in the direction indicated by the vertical arrow. Injection pressure 240 applied to the overmold 212 deforms or changes shape the cap 214. The change in shape of the cap 214 applies a radial force 242 (represented by the horizontal arrow) and causes a radial deflection of the plunger 202 in the direction indicated by the horizontal arrow against the inner wall 206 of the syringe barrel 204 to provide greater sealing pressure. The radial force 242 urges the first and second

annular ribs

220, 222 into the respective first and second

annular grooves

224, 226 to create a dynamic seal against the inner wall 206 of the syringe barrel 204. Thus, the sealing force between the plunger 202 and the inner wall 206 of the syringe barrel 204 is a dynamic function of the injection pressure 240. Accordingly, because the higher sealing force is only present for a brief duration during injection, syringe barrel 204 expansion due to creep is managed. This function may be used to define the pressure tolerance requirements of the syringe plunger system 200 for injection Pressure (PSI) versus time (mS). In one aspect, the syringe plunger system 200 may withstand an injection pressure of greater than or equal to 355psi for 30 seconds, and may withstand an injection pressure of greater than or equal to 405psi for 1 second, as shown, for example, in fig. 16. The elasticity of the plunger 202 enhancing the dynamic sealThe importance of which. The pressure range includes 0 to 2000PSI, depending on the material and type (e.g., CT or CV) injected. For CT injections, the maximum injection pressure is about 500PSI and the nominal operating pressure is about 150 to 350PSI. For CV injections, the maximum injection pressure is about 1500PSI and the nominal operating pressure is about 300 to 800PSI.

Fig. 5B is a cross-sectional view of one aspect of the syringe plunger system 200 with dynamic sealing shown in fig. 5A in a compressed state. As shown, injection pressure 240 applied to the overmold element 212 deforms or changes shape the cap 214. The change in shape of the cap 214 applies a radial force 242 (represented by the horizontal arrow) and causes radial deflection of the plunger 202 in the direction indicated by the horizontal arrow against the inner wall 206 of the syringe barrel 204 to provide greater sealing pressure. The radial force 242 urges the first and second

annular ribs

220, 222 into the respective first and second

annular grooves

224, 226 and/or against the sidewall 206 to create a dynamic seal against the inner wall 206 of the syringe barrel 204.

FIGS. 6-11 illustrate the angle θ included in the definition of the angle ₂ Several views of one aspect of the support ring 216 structure of the conical cap 252. Further details of support rings such as 216 can be found in U.S. Pat. Nos. 7,666,169 and 9,480,797, which are incorporated herein by reference. Fig. 6 and 7 are perspective views of the support ring 216. Fig. 8 is a plan view of the support ring 216. Fig. 9 is an elevation view of the support ring 216. FIG. 10 is a bottom view of the support ring 216, and FIG. 11 is a cross-sectional view of the support ring 216 taken along section line 11-11 shown in FIG. 10. Referring to fig. 6-10, the support ring 216 includes a tip 250, a conical cap 252, and an annular shoulder 254. The conical cap 252 defines an included angle θ that is greater than about 90 ° and less than about 120 ° ₂ . In the illustrated example, the included angle θ ₂ About 96 deg., although the included angle theta may be optimized ₂ To achieve a predetermined dynamic sealing force between the plunger 202 and the barrel (fig. 4 and 5A, 5B). The conical cap 252 may define one or more, or even a plurality of, apertures 234 to allow air to be expelled back out of the syringe barrel 204 and out of the fluid path. An annular groove 218 is defined between the conical cap 252 and the annular shoulder 254. Annular groove 218 is configured to snap-fit receive cap 214 (fig. 4 and 4)Fig. 5A, 5B). The conical cap 252 of the support ring 216 defines the internal volume 232. Although one embodiment of the support ring 216 is shown in fig. 6-11, other embodiments and configurations of the support ring 216 are contemplated, for example, support rings having different piston engagement mechanisms (such as described in U.S. patent No.7,666,169) and/or configurations that do not have an aperture 234 or have one aperture 234 in the conical cap 252. In aspects without the aperture 234 in the conical cap 252, compression during the injection process may compress air in the air chamber 230 or force air in the air chamber 230 out between the plunger cover 214 and the support ring 216.

Fig. 12 is a cross-sectional view of the syringe plunger system 200 with a dynamic seal in a transport configuration. In the shipping configuration, plunger 202 is at a pressure significantly below the nominal injection pressure. The syringe plunger system 200 includes a syringe barrel 204 defining an interior wall 206 and a plunger 202 disposed within the syringe barrel 204. Plunger 202 includes a defined included angle θ ₂ Support ring 216 at an included angle θ ₂ Greater than about 90 deg., and in one example about 96 deg.. As previously described, angle θ ₂ May for example have a value between about 90 ° and about 120 °. The support ring 216 includes engagement features for reversible engagement with a piston of a medication injector that reciprocates the plunger 202 within the syringe barrel 204. The support ring 216 defines at least one aperture 234 to allow air to be expelled back out of the syringe barrel 204 and out of the fluid path. Plunger 202 also includes a cap 214 configured to snap over support ring 216 into an annular groove 218 defined by support ring 216. The cap 214 also includes first and second

annular ribs

220, 222 configured to be received within respective first and second

annular grooves

224, 226 defined in the inner wall 206 of the syringe barrel 204 to form a dynamic seal under injection pressure conditions. The overmold 212 may be disposed over a cap 214.

As shown in FIG. 12, the angle θ ₃ Is defined between the support ring 216 and the cover 214 to define an air chamber 230 therebetween. The air chamber 230 defines a predetermined compliance volume such that when the syringe plunger system 200 is under injection pressure, the cap 214 and the overmold element 212 are subjected to axial forces and flexibly deform toCompressing the compliant volume defined by the air chamber 230. Under injection pressure conditions, the deformation applies a radial force to push the first and second

annular ribs

220, 222 into the respective first and second

annular grooves

224, 226 and/or against the sidewall 206 of the syringe barrel to form the primary and secondary dynamic seals, respectively. As previously discussed, the air chamber 230 may be configured to define a predetermined volume within a range from 0.1mL to 10mL. A gap 258 is defined between the support ring 216 and the inner wall 206 of the syringe barrel 204 when the plunger 202 is in the transport configuration and not under injection pressure. The configuration of the syringe plunger system 200 shown in fig. 12 in various compressed states is described below in connection with fig. 13-15.

Fig. 13 is a cross-sectional view of the syringe plunger system 200 with dynamic seals shown in fig. 12 in an initial compressed state. For example, a typical initial pressure range may vary from just greater than 0PSI to 100PSI. In the initial compressed state, an angle θ 'is defined between support ring 216 and cap 214 due to the applied pressure of the fluid against plunger cap 214' ₃ Less than the angle theta shown in fig. 12 ₃ . As shown in fig. 13, the gap 258' defined between the support ring 216 and the inner wall 206 of the syringe barrel 204 is smaller than the gap 258 shown in fig. 12 due to the lateral force exerted against the first and second

annular grooves

224, 226 by the first and second

annular ribs

220, 222. Included angle theta ₂ Maintaining an angle theta with respect to that shown in fig. 12 ₂ Are substantially the same.

Fig. 14 is a partial cross-sectional view of the syringe plunger system 200 with dynamic sealing shown in fig. 12 at an operating injection pressure. Depending on the material and type of injection (e.g., CT or CV), the operating injection pressure may vary from 150PSI to 800PSI. The angle θ defined between the support ring 216 and the cover 214 under operating pressure " ₃ Less than a defined angle θ 'between support ring 216 and cover 214 when plunger 202 is in an initial compressed state' ₃ . Accordingly, the gap 258 "defined between the support ring 216 and the inner wall 206 of the syringe barrel 204 when the plunger 202 is at the operating injection pressure is less than the gap 258' shown in fig. 13 because of the first annular rib 220 and the second annular rib 220The annular rib 222 exerts additional radial force against the first and second

annular grooves

224, 226. Under operating injection pressure, the first and second

annular ribs

220, 222 press against the sidewall 206 to create a dynamic seal. As shown, the included angle θ ₂ Maintaining an angle theta with respect to that shown in fig. 12 and 13 ₂ Are substantially the same.

Fig. 15 is a partial cross-sectional view of the syringe plunger system 200 with dynamic seals shown in fig. 12 in a compressed state near or beyond a maximum injection pressure. The maximum injection pressure may vary from 500PSI to 1500PSI, and in some examples may be as high as 2000PSI, depending on the material and type (e.g., CT or CV) of injection. Under high pressure conditions, the dynamic seal formed by the first and second

annular ribs

220, 222 pressing against the sidewall 206 may begin to leak. The threshold pressure at which this occurs is referred to as the blowby (blob-by) pressure. As shown in FIG. 15, under maximum injection pressure conditions, an angle θ "" 'is defined between the support ring 216 and the cover 214' ₃ Relatively small or near zero. As shown, the gap 258"' between the support ring 216 and the cap 214 has been reduced to near zero and has essentially eliminated the entire air chamber 230 at the maximum injection pressure. As shown in FIG. 15, under maximum injection pressure conditions, the included angle θ ₂ Maintaining the angle theta from that shown in fig. 12-14 ₂ Are substantially the same.

Fig. 16 is a graphical representation 300 of the maximum pressure that the syringe plunger system 200 described in connection with fig. 4-15 can withstand after a continuous pressurization cycle, according to one aspect. Pressure (PSI) is shown along the vertical axis and time (mS) is shown along the horizontal axis. The tip 250 (fig. 6-11) of the support ring 216 is nominally about 0.005". Curve 302 represents the pressure applied to the syringe plunger system 200. During the first period T1, the pressure applied to the syringe plunger system 200 is gradually increased (increased) from 0PSI to about 355psi,355psi approximating the operating pressure of one type of syringe plunger system 200. During a second period T2, 355PSI of pressure is maintained on the syringe plunger system 200. After the duration period T2, during a third period T3, the pressure is ramped up (increased) until a fault (e.g., a leak) occurs. As shown by curve 302, during the third period T3, the fault occurs at approximately 420 PSI.

Fig. 17 is a graphical representation 350 of the maximum pressure that the syringe plunger system 200 described in connection with fig. 4-15 may withstand after a sustained pressurization cycle, according to another aspect. Pressure (PSI) is shown along the vertical axis and time (mS) is shown along the horizontal axis. The tip 250 (fig. 6-11) of the support ring 216 is nominally about 0.005". Curve 352 represents the pressure applied to the syringe plunger system 200. During the first period T1, the pressure applied to the syringe plunger system 200 is gradually increased (increased) from 0PSI to about 365psi,365psi approximating the operating pressure of one type of syringe plunger system 200. During the second period T2, 365PSI of pressure is maintained on the syringe plunger system 200. After the duration period T2, during a third period T3, the pressure is ramped up (increased) until a fault (e.g., a leak) occurs. As shown by curve 352, during the third period T3, the fault occurs at approximately 400 PSI.

Fig. 18 is a graphical representation 400 of the relationship of seal pressure as a function of included angle for the plunger system 200 described in conjunction with fig. 4-15, according to one aspect. Pressure (PSI) is shown along the vertical axis and plunger angle θ is shown along the horizontal axis ₂ (degree). In this context, the plunger included angle is the included angle θ defined by the support ring 216 as described, for example, in connection with fig. 4-5B, 9, 11, and 12-15 ₂ . Bar chart 402 depicts the maximum pressure that can be tolerated by syringe plunger system 200, which is the included angle θ of support ring 216 ₂ Is measured as a function of (c). As shown, at an included angle θ of 90 ° ₂ The maximum pressure is about 505PSI. At an included angle theta of 92 DEG ₂ The maximum pressure is about 520PSI. At an included angle theta of 94 DEG ₂ The maximum pressure is about 575PSI. At an included angle theta of 96 DEG ₂ The maximum pressure is about 590PSI. At an included angle theta of 98 DEG ₂ The maximum pressure is about 580PSI. And at an included angle theta of 100 DEG ₂ The maximum pressure is about 575PSI. Thus, for the examples depicted in fig. 4-15, the data shows an included angle θ in the range of 90 ° to 100 ° ₂ Optimum angle of inclusion theta ₂ Approximately 96 deg., since this angle produces a dynamic seal that can withstand the maximum sealing pressure required for a particular application. However, it will be appreciated that included angle θ may be optimized ₂ To provide a dynamic seal that can withstand various maximum injection pressures. Thus, included angle θ is disclosed herein ₂ And the specific values corresponding to the maximum withstand pressure should not be construed as limiting the scope of the invention.

Thus, the included angle θ from the support ring 216 ₂ The volume of the defined air chamber 230 (see fig. 4, 5A, and 12-15) translates into the sealing pressure of the dynamic seal. Another way to gauge the effectiveness of the dynamic seal is to increase the volume of the air chamber 230 and measure the seal pressure limit of the syringe plunger system 200. The graphical representation 400 shown in FIG. 18 illustrates increasing the included angle θ of the support ring 216 ₂ How to increase (increase the volume of the air chamber 230) the dynamic pressure seal limit of the syringe plunger system 200. The sealing performance of the plunger 202 eventually exceeds the material strength of the syringe barrel 204 at 96 °, resulting in a stable level (plateau) in the sealing pressure limit.

Fig. 19 is a graphical representation 500 of the optimal gap size for the air chamber 230 described in connection with fig. 4, 5A, and 12-15 for dynamic sealing of the syringe plunger system 200 described in connection with fig. 4-15, according to an aspect of the present invention. Radial deflection (in inches) is shown along the vertical axis and axial deflection (in inches) is shown along the horizontal axis. The data points of the curve 502 may be used to develop an n-th order polynomial equation representing the conical dynamic seal of the syringe plunger system 200 in accordance with an aspect of the present invention. The optimal gap size for the air cavity 230 may be calculated to produce the optimal effect of the dynamic seal. This optimal effect is equivalent to maximum added compression for sealing. One non-limiting example of this calculation is shown below. As the air chamber 230 gap size increases, peak compression is reached before the assembly contracts on itself and compression actually decreases. Equation (1) below is an example of a 2 nd order equation derived from the data points of curve 502 for a seal radius of 0.9944 inches.

y＝1.3722x^2+0.2746x-0.001 (1)

While various details have been set forth in the above description, it will be appreciated that various aspects of a syringe plunger with dynamic sealing may be practiced without these specific details. For example, selected aspects have been shown in schematic form in the interest of brevity and clarity and have not been shown in detail.

It is worthy to note that any reference to "one aspect," "an aspect," "one form," or "a form" means that a particular feature, structure, or characteristic described in connection with the aspect is included in at least one aspect. Thus, the appearances of the phrases "in one aspect," "in an aspect," "in one form" or "in a form" in various places throughout this specification are not necessarily all referring to the same aspect. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more aspects.

While various forms have been described herein, many modifications, changes, substitutions, changes, and equivalents to the described forms will now occur to those skilled in the art. Also, where materials are disclosed for use in particular components, other materials may be used. It is, therefore, to be understood that the above description and the appended claims are intended to cover all such modifications and changes as fall within the scope of the disclosed forms. It is intended that the following claims cover all such modifications and changes.

All of the above U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications, non-patent publications referred to in this specification or listed in any application data sheet or any other published material, are incorporated herein by reference, to the extent they are consistent in their entirety. Thus, to the extent necessary, the disclosure as explicitly set forth herein supersedes any conflicting material incorporated herein by reference. Any material, or portion thereof, that is said to be incorporated by reference herein, but which conflicts with existing definitions, statements, or other disclosure material set forth herein is only incorporated to the extent that no conflict arises between that incorporated material and the existing disclosure material.

Those skilled in the art will recognize that the components (e.g., operations), devices, objects, and the accompanying discussion thereof described herein are used as examples for the sake of conceptual clarity and that various configuration modifications are contemplated. Thus, as used herein, the specific examples set forth and the accompanying discussion are intended to represent their more general categories. In general, the use of any particular example is intended to be generic, and the non-inclusion of particular components (e.g., operations), devices, and objects should not be construed as limiting.

With respect to substantially any plural and/or singular terms herein, those having skill in the art may translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. Various singular/plural permutations are not expressly set forth herein for sake of clarity.

While particular aspects of the present subject matter described herein have been shown and described, it will be apparent to those skilled in the art that, based upon the teachings herein, changes and modifications may be made without departing from the subject matter described herein and its broader aspects and, therefore, the appended claims are to encompass within their scope all such changes and modifications as are within the true spirit and scope of the subject matter described herein. It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim recitation to claims containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and/or "an" should typically be interpreted to mean "at least one" or "one or more"); the same holds true for the use of indefinite articles used to introduce claim recitations.

In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, typically means at least two recitations, or two or more recitations). Moreover, in such examples where a convention analogous to "at least one of A, B, and C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, and C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In such examples, where a convention analogous to "at least one of A, B, or C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, or C" would include but not be limited to systems that have A alone, B alone, C alone, both A and B together, both A and C together, both B and C together, and/or both A, B, and C together, etc.). It will be further understood by those within the art that, typically, transitional words and/or phrases (whether in the description, the claims, or the drawings) presenting two or more alternative terms, should be understood to contemplate the possibilities of including either, or both of the terms. For example, the phrase "a or B" will generally be understood as encompassing the possibilities of "a" or "B" or "a and B".

In summary, a number of benefits derived from employing the concepts described herein have been described. The foregoing description of one or more embodiments has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the precise form disclosed. Modifications or variations are possible in light of the above teachings. The form or forms were chosen and described in order to illustrate the principles and practical application to thereby enable one of ordinary skill in the art to utilize the various forms and with various modifications as are suited to the particular use contemplated. It is intended that the claims set forth herein define the full scope of the invention.

Claims

1. A method for enhancing a seal between a cylindrical sidewall of a plunger and an inside wall of a barrel, the method comprising:

pressurizing fluid within an interior volume of the syringe to an operating pressure, wherein the syringe comprises a plunger comprising:

a support ring comprising a first conical cap;

a cover disposed over and coupled to the support ring, wherein the cover comprises a second conical cap and the cylindrical sidewall, wherein the cylindrical sidewall comprises at least one annular rib; and

an air chamber defined between the first and second conical caps, the air chamber defining a predetermined compliance volume such that when the plunger undergoes injection pressurization, the cover deforms and flexes into the compliance volume, wherein a distal portion of the first conical cap forms an angle with a proximal portion of the second conical cap;

deforming the cover such that the angle between a distal portion of the first conical cap and a proximal portion of the second conical cap is smaller at an operating pressure than when the fluid is not at the operating pressure; and

deflecting the at least one annular rib in a radially outward direction against an inside wall of a barrel of the syringe when the angle is smaller.

2. The method of claim 1, wherein the seal between the at least one annular rib and the inside wall of the barrel is stronger when the at least one annular rib deflects radially outward.

3. The method of claim 1, wherein the at least one annular rib comprises a first annular rib and a second annular rib on a cylindrical sidewall of the plunger.

4. The method of claim 1, wherein the plunger further comprises a third conical cap disposed over a distal surface of the cap.

5. The method of claim 1, wherein the cap further comprises an inner flange to engage an annular groove on the support ring between a shoulder and the first conical cap.

6. The method of claim 1, wherein the at least one annular rib comprises a first annular rib and a second annular rib on the cylindrical sidewall, and

wherein deflecting the at least one annular rib in a radially outward direction comprises deflecting the first annular rib and the second annular rib in a radially outward direction against an inner sidewall of the syringe when the angle is smaller.

7. The method of claim 1, wherein pressurizing the fluid within the interior volume of the syringe comprises moving the plunger in a distal direction within a barrel of the syringe.

8. The method of claim 1, wherein the angle between the distal portion of the first conical cap and the proximal portion of the second conical cap is greater than 0 ° and less than about 30 ° when the fluid is not at operating pressure, and

wherein deforming the cover comprises deforming the cover under operating pressure such that the angle between the distal portion of the first conical cap and the proximal portion of the second conical cap is greater than 0 ° and less than about 30 °.

9. The method of claim 1, wherein the predetermined compliance volume of the air chamber is in a range between 0.1mL and 10mL when the fluid is not at an operating pressure, and

wherein deforming the cover comprises deforming the cover such that a volume of the air chamber is less than the predetermined compliance volume at an operating pressure.

10. The method of claim 9, wherein the volume of the air chamber is substantially zero at an operating pressure.

11. The method of claim 9, wherein deforming the cover such that a volume of the air chamber is less than the predetermined compliance volume at an operating pressure further comprises:

expelling air in the predetermined compliance volume through at least one aperture defined by the support ring proximate to the plunger to a barrel of the syringe.

12. The method of claim 1, further comprising moving the plunger in a distal direction within a barrel of the syringe.

13. The method of claim 12, further comprising delivering the fluid through an outlet port at a distal end of the syringe.

14. A fluid injection system, comprising:

a power fluid injector head comprising at least one piston; and

at least one syringe engaged with at least one plunger of the power fluid injector head,

wherein the syringe comprises:

a barrel defining an inner wall; and

a plunger located within the inner wall of the barrel, the plunger comprising:

a support ring comprising a first conical cap;

a cover disposed over and coupled to the support ring, wherein the cover comprises a second conical cap and a cylindrical sidewall, wherein the cylindrical sidewall comprises at least one annular rib; and

an air chamber defined between the first and second conical caps, the air chamber defining a predetermined compliance volume such that when the plunger is subjected to injection pressurization, the cover deforms and flexes into the compliance volume,

wherein a distal portion of the first conical cap forms an angle with a proximal portion of the second conical cap, an

Wherein the angle between the distal portion of the first conical cap and the proximal portion of the second conical cap is smaller when the plunger is under operating pressure than when the plunger is not under pressure due to deformation and flexing of the cover, and wherein the at least one annular rib deflects radially outward against the inner wall of the barrel when the angle is smaller.

15. The system of claim 14, wherein the at least one annular rib of the plunger cover comprises first and second annular ribs on an outer cylindrical sidewall, the first and second annular ribs forming a seal with an inner wall of the barrel.

16. The system of claim 14, wherein the first conical cap of the plunger defines a clip top angle greater than about 90 °.

17. The system of claim 16, wherein the first conical cap of the support ring defines a clip top angle greater than about 90 ° and less than about 120 °.

18. The system of claim 14, wherein an angle defined between the first conical cap of the support ring and the second conical cap of the cover is greater than 0 ° and less than about 30 °.

19. The system of claim 14, wherein the predetermined volume of the air chamber is selected from a range between 0.1mL _ and 10mL _.